1. Field of the Invention
The present invention relates to a valve assembly useful for routing fluid through a piping system. Specifically, the present invention relates to an aseptic valve assembly for routing a flowable food product on a packaging machine.
1. Description of the Related Art
Aseptic packaging of milk, juice, other flowable foods, and other products requires that the product must be initially sterilized or otherwise treated, as by pasteurizing it. Then, throughout the packaging operation, the product must be kept sterile. Care must be taken to ensure that the product is not contaminated with cleaning fluids, lubricants, ambient air, or non-sterile matter. If the product is not aseptic (for example, properly-handled conventionally pasteurized milk is not aseptic), stringent steps must be taken to avoid trapping the product in any crevice, pocket, dead end or mechanism, as an entrapped product which is not aseptic when it enters may sustain microbial growth and may form unsightly lumps or particles. This machinery must be designed to facilitate regular inspection of any mechanism which might deteriorate and thus trap the product or expose it to contaminants.
Block-and-bleed valve assemblies, also known as "leak detector" valves, have been used to ensure that two process streams, like a sanitary product and a cleaning fluid which are to flow alternately through the same piping, do not mix, either during normal operation or due to leakage or other failure of a single valve. Two valves are provided in series in a block-and-bleed valve. The inlet valve is located at the inlet to the valve chamber, and is normally closed to stop the flow of one of the fluids into the chamber. The outlet valve is located at the outlet to the valve chamber, and is normally closed to stop the flow (usually, unintended backflow) of the other of the fluids into the valve chamber. A normally-open drain in the valve chamber, which is also valved, facilitates leak detection. For example, the drain tube leaving the valve can be transparent so any leakage into the drain may be seen by an operator.
In conventional block-and-bleed valves, two or more separate valve bodies are assembled to form the complete valve assembly, as by welding a tee of tubing between the outlet ports of the respective valve bodies. The tubing and valve outlet passages in the resulting assembly define a "dead leg" which is longer than optimal. Dead legs and poorly drained internal valve surfaces represent places where a product or chemicals may undesirably pool.